Sintered plate of polyvinyl chloride resin and method of making the same

ABSTRACT

A plate, prepared by sintering a mixture of 100 parts by weight of polyvinyl chloride resin and from 0.1 to 10 parts by weight of a surface active agent, which has a tensile strength of at least 0.7 kg/mm2, has very high wettability and permeability for water, and resistance to combustion. Among other uses, the plate may serve in packings for cooling towers due to these excellent properties mentioned. The invention also relates to a method of making the plate.

United States Patent Katagiri et al.

[ Feb. 11, 1975 SlNTERED PLATE OF POLYVINYL CHLORIDE RESIN AND METHOD OF MAKING THE SAME Inventors: Kotaro Katagiri, Tokyo; Yoshio Nakamura, Saitama-ken; both of Japan Assignee: Shinetsu Chemical Company,

Tokyo, Japan Filed: Aug. 21, 1972 Appl. No.: 282,353

Related U.S. Application Data Continuation of Ser. No. 63,148, Aug. 12, 1970, abandoned.

Foreign Application Priority Data Aug. 26, 1969 Japan 44-67483 U.S. Cl. 260/92.8 A, 260/2.5 M, 202/239 Int. Cl. C08f 1/88, C08f 3/30 Field of Search 260/25 M, 92.8 A

[56] References Cited UNITED STATES PATENTS 2,960,727 11/1960 Bradshaw 18/55 2,963,746 12/1960 Webb et a1. 18/57 2,984,869 5/1961 Honey et a1. 18/48 3,117,113 1/1964 Tudor 260/928 3,654,065 4/1972 Dorogi 161/159 Primary Examiner-Joseph L. Schofer Assistant Examiner-John Kight, lll Attorney, Agent, or Firm-Toren and McGeady [57] ABSTRACT A plate, prepared by sintering a mixture of 100 parts by weight of polyvinyl chloride resin and from 0.1 to 10 parts by weight of a surface active agent, which has a tensile strength of at least 0.7 kg/mm has very high wettability and permeability for water, and resistance to combustion. Among other uses, the plate may serve in packings for cooling towers due to these excellent properties mentioned. The invention also relates to a method of making the plate.

3 Claims, 2 Drawing Figures PATENIEBFEM 1 I975 (1.8657 9 9 INVENTORS K 07A R0 KA 7: g, Yosmo NAKAMURA H u 5 BY ATTORNEYS SINTERED PLATE OF POLYVINYL CHLORIDE RESIN AND METHOD OF MAKING THE SAME This is a continuation of application Ser. No. 63,148 filed Aug. 12, 1970, and now abandoned.

SUMMARY OF THE INVENTION This invention relates to a sintered plate comprising a base of polyvinyl chloride resin, and as an admixture thereto, a surface active agent. The sintered plate has improved tensile strength, wettability by water and permeability thereto, and is highly resistant to combustion, properties which make the plate of the invention very useful as packing for cooling towers. The invention also relates to a method for making the plate.

Wood, bamboo, paper impregnated with synthetic resins, or sheets or plates of synthetic resins, have been used as packings for cooling towers. Of these substances, packings of wood or bamboo, which are lowpriced, are apt to absorb water and get deformed and are subject to decay; moreover, they are not durable because of their combustibility, especially in winter, when only air is passed through the cooling equipment instead of water. On the other hand, packings of paper impregnated with synthetic resins are of low strength, durability and wettability, while packings of sheets or plates of synthetic resins, although much superior to others in strength and durability, have the disadvantages of hardly getting wet. Therefore, before they are put to use, they must be subjected to surface treatment, with, for example, a hydrophilic substance; this results in high processing costs. Furthermore, it is a shortcom ing of the thus treated synthetic resin plates that the treated surface deteriorates in use and their characteristics decline in the long run, so that they are not capable of serving the purpose satisfactorily.

It is an object of the invention to provide a sintered plate consisting essentially of polyvinyl chloride resin which has high tensile strength, wettability by and permeability for water, and which is substantially incombustible.

lt is another object of the invention to provide a sintered plate ofthe type mentioned which can be stacked to form a block for insertion as a packing into a cooling tower.

It is yet another object to provide a method for making the sintered plate and the block for insertion into a cooling tower.

Other objects and advantages of the invention will become apparent from the following description and the accompanying drawing.

The sintered plate of polyvinyl chloride resin of the present invention, having a tensile strength of at least 0.7 kg/mm is prepared by sintering a mixture of 100 parts by weight of polyvinyl chloride resin and from 0.1 to 10 parts by weight of surface active agent. As the plate contains a surface active agent and its structure is porous, its wettability by water is higher than that of the materials used heretofore. Furthermore, as water gets diffused in the sintered plate or toward its surface by capillarity, a packing can be made by processing this sintered plate which has a cooling capacity over its entire surface, achieving a remarkable cooling effect. In addition, the sintered plate of this invention possesses thermal plasticity, so that it can be easily processed into any desired shape. It is low in bulk density, as low as from to 80% of that of a sheet or plate of polyvinyl chloride resin hitherto employed, so that it lends itself to the use of insert into cooling towers, in which a number of such plates are to be packed and which can be made small in size and light in weight. As the sintered plate of the invention has a tensile strength of at least 0.7 kg/mm it comes up to the standard requirements of a packing for a cooling tower both in strength and durability.

1n the following a more detailed description of the plate according to the invention will be given. The plate of polyvinyl chloride resin of this invention is prepared by sintering polyvinyl chloride resin, having a particle size of at least by weight in the range of from 10 to p. and containing a prescribed amount of surface active agent. 1f the polyvinyl chloride resin is of substantially larger particle size, no sintered plate of uniformly porous structure and high tensile strength, will be obtained. If, on the other hand, the polyvinyl chloride resin is of considerably smaller particle size, the porosity of the plate will decrease, thereby lowering the water-retention capacity of the plate, resulting in a plate 'of low cooling effect.

As mentioned above, the surface active agent contained in the polyvinyl chloride resin is considered to be essential to the improvementof the water-wettability of the plate and the quantity of the surface active agent has to be in the range of from 0.1 to 10 parts by weight based on 100 parts by weight of polyvinyl chloride resin. lf the polyvinyl chloride resin has been prepared by the ordinary suspension polymerization method, an amount of surface active agent in the range mentioned above may be added to and mixed with the polyvinyl chloride resin, but if the polyvinyl chloride resin has been prepared by emulsion polymerization and already contains some surface active agent, such an amount of surface active agent which gives the final content of from 0.1 to 10 parts by weight should be added to and mixed with 100 parts of the polyvinyl chloride resin. The degree of polymerization of the polyvinyl chloride resin does not influence the properties of the sintered plate to a considerable extent, but polyvinyl chloride resin of from 700 to 1,500 polymerization degrees should be preferably used.

Any surface active agent may be: added to and mixed with the polyvinyl chloride resin, as long as it serves to improve the water-wettability of the sintered plate; it may be selected from the group consisting of nonionic surface active agents, such as polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, and block copolymer of polyoxyethylene and polyoxypropylene; of anionic surface active agents, such as alkyl aryl sulfonate, alkyl sulfonate, alkyl sulfate, alkyl ether sulfate, and sulfosuccinic acid ester; and of cationic surface active agents, such as higher amine salt of a halogen acid, halogenated alkyl pyridinium, polyoxyethylene alkyl amine, polyoxyethylene alkyl amide, and quaternary ammonium salt.

The method of preparing the sintered plate of this invention, having a tensile strength of at least 0.7 kg/mm comprises spreading polyvinyl chloride resin of a particle size as indicated and containing some of the above-mentioned surface active agents, for example, on a metal plate, and scraping it or compressing it lightly with a roller, into a plate, 0.3-1.0 mm in thickness; the plate is then heated at a temperature between and 300 C for a period of from 1 to 30 minutes, and cut into the desired size.

The sintered plate can be used as a packing for a cooling tower, as it is, or, if necessary, after heated above its softening point or, preferably at a temperature between 60 and 150 C so that it may be molded The sintered plates, A, B, and C were processed into corrugated plates with a pitch of 30 mm and a height of 15 mm, and 20 sheets of each kind were stacked, one on top of the other, in such a way that the grooves on into a desired shape or pattern, such as a corrugated, 5 the adjoining plates would cross each other at an angle wrinkled, dimpled, embossed or punched plate. A numof 60 C, until a block, 600 mm long, 200 mm wide and her of such sintered plates are stacked in layers so that 300 mm thick, was obtained to be used as packing; they will form a block, which is placed in the cooling (Samples X, Y and Z) given in Table 2. tower to be employed as packing. 24 samples were prepared of each kind, and they were placed in a cooling tower, as illustrated in FIG. 2, IN THE DRAWINGS: on a supporting member 5. The packing density was 90 m /m Air was then introduced into the cooling tower 1 l a sllltered l and .through louvers 6, provided on the lower portion ofthe a longltudmal secfnon of a Coolmg towertower housing, while water was introduced through a Referring now to the drawmgs, FIG. 1 shows by way 15 pipe 7 and Sprayed Over packings 3 by means of Sprim of m a blofik smtered plat? capable of bemg klers 8. The spraying was effected so that air and water a coolmg l the figure l a l" came into contact with each other in the packing. The gatFd lmered plate Wlth a number of gmqves 2 on water descending through the packings was collected in which [5 so.placed that the grooves of the ad acent plate a tank 9 provided at the bottom of the cooling tower, are in Opposite dlrectlon' A number of such plates and then discharged from the cooling tower through a ranged in layers form a packing 3 to be inserted in the pipe The air ascending through the packings and Coolmg w passing an eliminator 11 was discharged from the cool- The details of the present invention Will be further ing tower through an exit 13, by means of a fan 12' described in the following examples, in which polyvinyl The cooling capacity of the cooling tower was tested chloride resins employed as raw materials are of the by passing air through it at the rate of 10 X 3 different kinds, designated as A, B and C; all parts are kg/mzrhr, and also by passing water therethrough a by i I different rate and determining the ratio of water to air. Resin A: To 100 parts of polyvinyl c l f resm P The results obtained are given in Table 2 as relations par.ed by sllspenslon polymerlzatlon 90% by between the volume coefficient, Q, of the cooling we'ght of whlch had a Pamela Slze of from 10 to tower and the flow ratio of water to air, L/G. In the tal50 p. while the balance had a particle size of less ble, Sample S represents packings prepared of than 10 and WhQSe average polymenzatlon mercial polyvinyl chloride resin sheets, having the same g and bulk density were 830 and respec' surface area and permeability resistance as the packl we a mlxture of 5 parts of dlocty] ings of the present invention. Sample S was tested as a drum sulfosuccmate and 5 parts of water-ethanol Control- Solunon 8 after havmg been well mixed the mix- The volume coefficient of the cooling tower was calf was drled at room temperature culated by means of the following equation: Resin B: A mixture was prepared by adding 3 parts of sodium tridecyl sulfate to 100 parts of polyvinyl Q KaV/L chloride resin prepared by suspension polymeriza- 40 9" and hill/mg an ilvemge polymcnzmlorl degfee where K is an over-all heat transfer coefficient based on l m" f bull? flenslty of and a pamclc the enthalpy difference, a is the contact area per unit l lmm n 100 I volume, V is the volume of packing and L the flow of Rosin C: lhlS was a polyvinyl chloride resin prepared water.

by emulsion polymerization, having an average po- 45 lymerization degree of 1,070, a bulk density of bl 0.56, and a particle size of from 10 to 150 u, and Ta e 2 containing 1% of a surface active agent, sodium I lauryl ether sulfate, added at the time of polymer- Sample volume wemclem of tower (Q) ization to act as an emulsifier. MG X Y Z s 0.6 0.74 0.88 0.80 0.47 EXAMPLE 1 1:8 8:88 8:88 8:88 8:88 Resins A, B and C were each spread about l mm 18 832 813% 8:32 8:}; thick on an iron plate, and then heated in a sintering furnace under the conditions given in Table 1, whereby sintered plates were obtained with physical properties As may be seen from the table, the samples of the also indicated in Table 1. present invention showed a remarkably improved cool- Table l Sintered plate A B C Sintering condition (C/min.) 210/5 200/9 220/6 (Tensile strength (kg/mm) 0.8 1.2 L8 Physical properties (Sprcad of water (mm (Note 1) 292 346 32l (Height of water (mm) (Note 2) 73 ing capacity when L/G was in the range of from 1 to 2 which is an ordinary working condition for a cooling tower. Therefore, if the sintered plates are employed as packings for a cooling tower, the size of the cooling tower can be made smaller, thus affording a great economical advantage.

EXAMPLE 2 Various sintered plates were made of Resin A by the methods given in Example 1, and the tensile strength and the cracking angle of each of them were measured, whereby the results shown in Table 3 were obtained.

When the value of the tensile strength was below 0.7

Table 3 Tensile strength in kg/mm 0.1 0.4 0? 1.0 1.3 L6 Cracking 19 22 26 32 4l 55 angle As may be seen from this Table the cracking angle was considerably higher when the tensile strength was above 0.7 kglmm What is claimed is:

l. A sintered porous plate for use as packing in a cooling tower, said plate being formed of polyvinyl chloride homopolymer resin having a tensile strength of at least 0.7 kg/mm and containing a mixture of 100 parts by weight of polyvinyl chloride resin, at least by weight of which has a particle size of from 10 to 150p, and from 0.1 to 10 parts by weight of one or more surface active agents.

2. A method for preparing a sintered plate as claimed in claim 1 which comprises the steps of mixing parts by weight of polyvinyl chloride homopolymer resin and from 0.1 to 10 parts by weight ofa surface active agent, spreading the mixture uniformly over a metal plate and thereafter heating it at a temperature of from 180 to 300 C for a period of from I to 30 minutes. v

3. The method claimed in claim 2 wherein at least 90% by weight of the polyvinyl chloride resin has a particle size in the range of from 10 to u. 

1. A SINTERED POROUS PLATE FOR USE AS PACKING IN A COOLING TOWER, SAID PLATE BEING FORMED OF POLYVINYL CHLORIDE HOMOPOLYMER RESIN HAVING A TENSILE STRENGTH OF AT LEAST 0.7KG/MM2, AND CONTAINING A MIXTURE OF 100 PARTS BY WEIGHT OF POLYVINYL CHLORIDE RESIN, AT LEAST 90% BY WEIGHT OF WHICH HAS A PARTICLE SIZE OF FROM 10 TO 150U, AND FROM 0.1 TO 10 PARTS BY WEIGHT OF ONE OR MORE SURFACE ACTIVE AGENTS.
 2. A method for preparing a sintered plate as claimed in claim 1 which comprises the steps of mixing 100 parts by weight of polyvinyl chloride homopolymer resin and from 0.1 to 10 parts by weight of a surface active agent, spreading the mixture uniformly over a metal plate and thereafter heating it at a temperature of from 180* to 300* C for a period of from 1 to 30 minutes.
 3. The method claimed in claim 2 wherein at least 90% by weight of the polyvinyl chloride resin has a particle size in the range of from 10 to 150 Mu . 